Founding Engineer

About the role

As a Founding Engineer, you'll architect and build the core AI agents and infrastructure that power precision outbound at scale — then make them accessible through beautiful, intuitive interfaces. You'll work directly with customers, shape product direction, and own critical systems that drive revenue for 40+ YC companies and growing.

What You'll Build

- AI agents that discover hyper-targeted leads by understanding ideal customer profiles, conference attendees, hiring signals, and more.

- Real-time content monitoring systems that track what prospects are posting, sharing, and engaging with across social platforms.

- Multi-channel sequence orchestration across email and LinkedIn, managing dozens of email domains and sender accounts.

- Enterprise-grade infrastructure that scales to hundreds of concurrent users — multi-tenant architecture with role-based access control, end-to-end encryption, SOC 2-ready audit logging, and rate limiting built in from day one.

- Polished user interfaces that turn complex outbound workflows into experiences sales teams can set up in minutes.

We're Looking For

- 1–6 years of experience building production systems and user-facing features.

- Full-stack expertise — strong with TypeScript, React, Next.js, and Python. Systems thinking — you understand distributed systems, concurrency, and performance optimization.

- Product mindset — you talk to customers, understand their pain, and ship solutions that solve real problems.

- High agency — you identify problems and fix them without being asked.

Bonus Points

- Experience with AI/ML, particularly LLMs, prompt engineering, or building AI agents.

- Previous startup experience or experience building successful B2B SaaS products.

- Design sense — you can build UIs that don't just work, but feel great to use.

What We Offer

- Significant equity in a fast-growing company backed by Y Combinator.

- Direct customer impact — your code powers outbound for dozens of high-growth startups.

- Work closely with 2x YC founders (Harvard/MIT CS) who've built and sold before.

- Competitive compensation — $150k–$230k base salary plus equity.

- Full benefits — health, dental, vision, unlimited PTO.

- San Francisco office — collaborate in-person with the team.

About Cardinal

Cardinal is the AI platform for precision outbound. "Spray and pray" outbound is dead — the best sales teams operate with extreme precision, but doing this well means stringing together 10+ tools and hiring a GTM engineer. Cardinal replaces all of that. Our AI agents find hyper-targeted leads, continuously monitor what prospects are posting on social media, generate personalized snippets based on shared context, and orchestrate end-to-end outbound workflows across email and LinkedIn. We also capture inbound from website visitors, product signups, and ad impressions — qualifying and routing them into sequences automatically. We run outbound for 40+ YC companies including Mintlify, Greptile, and Luminai, and we're growing fast.